A world-class tennis player can serve a tennis ball at 150 mi/h (about 67 m/s). The length of a tennis court is 78 ft. Approximately how long does an opponent have to react from the instant the ball is served
until the ball reaches the opponent?

Jason is a body builder. despite being more fit, he weighs more than his brother ryan, who is the same height. which is a possible reason? a. jason has more muscle mass than ryan does. b. jason has more body fat than ryan does. c. jason has more muscle mass and body fat than ryan does d. jason has less body fat than ryan does.

Aprotein molecule in an electrophoresis gel has a negative charge. the exact charge depends on the ph of the solution, but 30 excess electrons is typical. what is the magnitude of the electric force on a protein with this charge in a 1600n/c electric field? write in two significant numbers, and also in newton

Another word for electromagnetic energy is a. heat b. force c. matter d. radiation